This is a two part investigation into cellular energy metabolism. We shall study biological electron and proton transfer processes which are linked to the conversion of free energy into that capable of driving ADP phosphorylation. We exploit the unique properties of the photosynthetic bacterium Rps. sphaeroides and its isolatable reaction center protein in combination with mitochondrial respiratory complexes in reconstituted membranes. The first part approaches the problem by physical chemical techniques involving single turnover flash activation and rapid analysis (a) to count the electrons and protons involved in energy coupling to correlate them with ATP production (b) to reveal time resolved dynamics and equilibria of component-component interactions (eg., cytochrome c reaction center) (c) to study states of kinetically relevant yet short lived intermediates (eg., ubisemiquinone) not normally measurable by steady state techniques, and (d) to study the vectorial aspects of electron and proton translocations, and influences of time-resolved local and delocalized transmembrane functions. These studies are applied to determine factors at the membrane structural and dynamic level which influence the thermodynamics kinetics of the processes in vivo, and lead to the second part of the study. Unlike mitochondrial membranes, the chromatophore membranes, and its functionally reconstituted models, are well suited for investigation at the molecular level using X-ray and neutron diffraction techniques. Determination of these structural parameters at the molecular level as related to the energy coupling described in the first part, bring those physical-chemical approaches firmly into the structural realm. The two parts thus provide an unusual continuum of effort to acquire an improved knowledge of how respiratory energy in biological systems is handled at the molecular level, and of the structural and dynamic constraints for its efficient conservation and utilization.